Restoring a Nexus 7 from a USB stick rather than PC

Greg · 17 Jan 2015 at 17:48

Guys,

Have a Nexus 7 that has no OS on it, I can't connect it to my PC as it's not recognised and the generic USB drivers from google won't work.

I think I've wiped everything from the Nexus as it has no data what so ever, no os, no personal date or apps!

It does, however, have a copy of TWRP that I'm able to access by pressing the Power and Vol down button.

I've been trying to connect it to my PC running Windows 7 in order to restore it to a factory image but as described above, I'm having zero success.

I thought about maybe building an SD card or USB stick and using this via a converter (as it is recognised in the bootloader) to then restore the nexus back to factory?

Sorry If I've been a bit vague but I'm at a complete loss.

I've searched high and low on the net but there are no guides to help that don't involve the device being connected to a computer.

Any help greatly appreciated!

Thanks

Rroff · 17 Jan 2015 at 17:58

Does it recognise a USB stick via an OTG cable? - not something I've much experience of but I seem to remember you could select a file in the recovery manager that was on a USB stick connected that way.

I believe the filesystem format of the USB stick matters as well.

Greg · 17 Jan 2015 at 18:27

Thanks for the reply!

Yes, it does recognise the USB stick - I guess I'm not sure what files to load onto it to restore from?

does anyone know of a package that i could dump onto or build onto the stick that i could then restore from?

TYIA

Orcvader · 17 Jan 2015 at 18:50

Have you tried using these drivers?: http://www.koushikdutta.com/post/universal-adb-driver

The stock Google drivers doesn't properly work for me on my Nexus 10 when in bootloader mode but this works fine.

Greg · 18 Jan 2015 at 11:39

Orcvader! You're a star!!!

Those USB drivers work fantastically!

The next hurdle is the following:

I've downloaded what I thought was the right package from the Google website for my Nexus 7 but it's not wanting to flash.

I managed to get to a point where it says (using flash-all.bat) that:

checking product...
FAILED

Device product is 'grouper' .
Update requires 'flo' .

Now, I've tried every package from the Google website that is available for a Nexus 7 with no success.

Any ideas? Even if I can get just a custom OS on there to start the ball rolling so I know it can work?

Thanks

Greg

Orcvader · 18 Jan 2015 at 11:50

Which Nexus 7 is it? You need to remember there was a 2012 and 2013 version, and the mobile/wifi only models in turn are also treated as seperate devices.

Grouper seems to point at the Nexus 7 2012 wifi model however, so this should work: https://dl.google.com/dl/android/aosp/nakasi-lrx22g-factory-2291c36b.tgz

Greg · 18 Jan 2015 at 12:12

That's great, I've got further than I did before.

It's now saying that my Device version-bootloader is '3.41'.
Update requires '4.23'

You're right, it's a Nexus 2012 model (it's not got a camera on the back, jsut a forward facing one).

Know how to update my bootloader? :sigh!:

Orcvader · 18 Jan 2015 at 12:35

Do you have ADB installed on your PC?

I've extracted the 4.23 bootloader from the image for you: Removed link

Go into bootloader/fastboot mode and then do:

Code:

fastboot flash bootloader bootloader-grouper-4.23.img

Once it's finished, if it doesn't restart do:

Code:

fastboot reboot-bootloader

And then try running the factory restore software again.

Alternatively, you can manually flash the factory image from fastboot:

Code:

fastboot erase boot
fastboot erase cache
fastboot erase recovery
fastboot erase system
fastboot erase userdata
fastboot flash bootloader bootloader-grouper-4.23.img
fastboot reboot-bootloader
fastboot -w update image-nakasi-lrx22g.zip

Greg · 18 Jan 2015 at 13:46

Ok, tried both methods. They both seem to get some of the way there but ultimately they both deliver the same error:

Signature mismatch (displayed at the top left of the Nexus).

On the device I have:

FASTBOOT MODE
PRODUCT NAME - grouper
VARIANT - not defined yet
HW VERSION - ER3
BOOTLOADER VERSION - 3.41
BASEBAND VERSION - N/A
SERIAL NUMBER - XXXX
SIGNING - not defined yet
LOCK STATE - UNLOCKED

Thanks for your help - I think we're making progress, but one step at a time?! Hopefully we'll get there eventually?!

Orcvader · 18 Jan 2015 at 14:05

Hmm, looks like the bootloader image from certain factory images causes that error.

Try this one, this one is from JWR66V which will work: Oddly a non-working one either

Greg · 18 Jan 2015 at 14:13

Will do, I'll let you know how I get on.

Greg · 18 Jan 2015 at 14:16

Same 'Signature Mismatch'

Oh deary me, maybe I have to do it in stages? Is there another one that I could use, just to see if it'll take 'a' bootloader.img?

Greg · 18 Jan 2015 at 14:19

Found this:

http://forum.xda-developers.com/showthread.php?t=2417097 and used this one. Signature seems to work and I'm currently running flash-all.bat

Will report back and let you know. thanks for the help so far!!!

Greg · 18 Jan 2015 at 14:37

All sorted, currently going through the setup process.

Thank you so much for your help!

Regards

Orcvader · 18 Jan 2015 at 15:25

That's odd, that's the very same thread I got the the working bootloader from

.

Glad your Nexus 7 is alive again though!

Greg · 18 Jan 2015 at 20:57

Strange!! Still, all is working now and I'm posting to you from my (finally) working nexus! Cheers for the help!

Greg